Abstract:

Objective To understand the prevalence of echinococcosis in Nagqu Prefecture in Tibet Autonomous Region. Methods A stratified cluster sampling method was used to select villages in 10 counties(districts) in Nagqu Prefecture from August to October, 2016. B ultrasound examination was performed in residents aged > 1 year, to calculate the morbidity rate of hydatid disease and estimate the prevalence and the case number. The prevalence of hydatid disease in intermediate hosts including cattle, sheep and rodents was investigated by visceral dissection combined with PCR. Echinococcus antigen in dog fecal samples was determined by ELISA. Knowledge on echinococcosis prevention and control was surveyed in 20 residents randomly selected in each village and grade 4-6 students in a primary school in each county by questionnairing. Comparison of hydatid disease prevalence among different populations was performed by χ² test. Results A total of 11 897 residents in 58 villages of 11 counties(districts) received B ultrasound, of whom 382 showed hydatid disease (3.21%). The prevalence in human population was estimated to be 3.37%, and the number of cases in the Prefecture was estimated to be 15 565. The 11 counties(districts) were all found with cystic echinococcosis cases and 7 were also found with alveolar echinococcosis, dominated by cystic echinococcosis (88.74%, 339/382). Among populations in different counties(districts), the prevalence was highest in Andou County(6.00%, 50/833), and lowest in Bange County (1.44%, 12/833), with a significant difference among counties(districts)(χ² = 43.22, P < 0.05). The prevalence in females was 3.66% (236/6 451), significantly higher than that in males (2.68%, 146/5 446) (χ² = 8.77, P < 0.05). Among different age groups, the prevalence was highest in the age group of ≥ 80 years (10.00%, 8/80), and lowest in the age group of 1-9 years (0.3%, 5/1 665), with a significant difference among age groups (χ² = 123.29, P < 0.05), showing a trend of increase with age (χ²_trend =123.29, P < 0.05). Among different occupations, the prevalence was highest in other occupations (5.94%, 13/219), and lowest in students (0.19%, 2/1 075) (χ² = 76.51, P < 0.05 among occupations). Among populations with different education levels, the prevalence in the educated (2.61%, 88/3 377) was lower than that in the illiteracy (3.45%, 294/8 520) (χ² = 5.29, P < 0.05) (χ² = 15.62, P < 0.05 among education groups). The prevalence in pastoral area (3.37%, 339/10 072) was higher than that in semi-agricultural and semi-pastoral area (2.36%, 43/1 825) (χ² = 4.75, P < 0.05). Rodents were investigated only in Biru County. A total of 304 Ochotona curzoniae were examined, with an infection rate of 0.33% (1/304). A total of 366 livestock (cattle and sheep) were examined, with a prevalence of 5.74% (21/366), highest in Shenzha County (32.5%, 13/40). The positive rate of Echinococcus antigen in dog fecal samples was 10.08% (109/1 081). The populational qualified rate on knowledge of echinococcosis prevention was 31.01% (824/2 657), being higher in pupils (34.29%,539/1 572) than in residents (26.27%,285/1 085) (χ² = 18.93, P < 0.05). Conclusion Both cystic echinococcosis and alveolar echinococcosis are prevalence in Nagqu, an estimated prevalence of 3.37%. More attention should be paid to females, herdsmen and those with less education, and residents in pastoral area.

Key words: Echinococcosis, Prevalence, Tibet Autonomous Region, Nagqu Prefecture